Luminescent ultra-small gold nanoparticles obtained by ion implantation in silica

The room temperature photoluminescence properties of ultra-small Au nanoclusters (made by 5–10 atoms) obtained by ion implantation in silica are presented. The results show a broad and intense luminescent emission in three different spectral regions around 750 nm, 980 nm and 1150 nm. The luminescence properties of the molecule-like Au clusters have been also correlated to the energy-transfer process to Er3+ ions in Au–Er co-implanted silica samples. A partial quenching of the 980 nm component is observed due to the Er3+ absorption level at 980 nm that acts as a de-excitation channel through which the photon energy is transferred from the Au nanoclusters to the Er ions, eventually producing the Er-related emission at 1.5 microns.